Nocturia

A guide to assessment and management

Background

Nocturia is a common cause of sleep disturbance affecting up to 40% of the adult population.

Objective/s

This article provides a framework for the management of nocturia. Based on the frequency volume chart, nocturia can be divided into three categories: global polyuria, nocturnal polyuria and bladder storage disorders. Differentiating between these categories enables effective targeting of treatment.

Discussion

Although nocturia is one of the most bothersome urinary symptoms, it has generally been poorly understood and managed. Aetiology is often multifactorial and includes systemic medical disease, lower urinary tract pathology, sleep disorders and behavioural and environmental factors.

Nocturia is ‘waking at night one or more times to void’. Each void is preceded and followed by sleep. ‘Night time’ is considered the hours of sleep whenever they occur, day or night. Being in bed but not asleep, does not constitute night time.1

The impact of nocturia on quality of life

Nocturia has a profound impact on quality of life, being comparable to gout, hypertension, diabetes and angina in terms of disease burden2

Nocturia typically becomes bothersome to patients when it occurs more than two times per night3

The severity of sleep impairment increases with the number of nocturnal voids3

Epidemiology

The prevalence of nocturia increases with age. More than 70% of people aged 70 years and over are affected.8 A substantial proportion of younger adults are affected with up to 30% of those aged 20–40 years voiding at least once per night.6 Younger sufferers are more likely to be female, however, prevalence is similar in both genders in older patients.8,9

Circadian control of urine production

Antidiuretic hormone (ADH) is released by the posterior pituitary and increases water reabsorption at the renal collecting tubule. Normally, ADH increases during sleep resulting in smaller volumes of concentrated urine.10 In elderly patients with nocturia this rhythm is often blunted with reduced nocturnal levels of ADH. This may be partly responsible for the increased prevalence that occurs with advancing age.11

Classification of nocturia

Nocturia can be categorised into three clinical entities based on the pattern of 24 hour urine (Figure 1):

nocturnal polyuria

global polyuria

bladder storage disorders.

Figure 1. Classification of nocturia

The frequency-volume chart

A frequency-volume chart (FVC) – or 'voiding diary' – distinguishes between the three categories of nocturia.

Charts should include:

volumes and times of urination for a 24–72 hour period1

beginning and end of sleep periods

time, type and volume of fluids ingested.12

Giving clear instructions before patients complete the chart improves compliance and eliminates the need for multiple diaries. It is usally more convenient for patients to choose a time when they are mostly at home to complete their voiding diary. The period recorded needs to be representative of the patient's typical symptoms. Once the diary has been completed by the patient, important values can be calculated (Table 1).

Table 1. Definitions of terms derived from the frequency-volume chart

Term

Definition

Nocturia

Number of voids recorded during a night's sleep, each void is preceded and followed by sleep

Night time

Time spent asleep

24 hour voided volume

Total volume of urine voided in a 24 hour period

First morning void

The first void after waking with the intention of rising

Nocturnal urine volume

Total volume urine passed during the night:

includes the first morning void

excludes the void before going to bed

Maximum voided volume

Largest single volume voided (usually between 300–600 mL)

Pathophysiology

Global polyuria

Global polyuria is continuously raised urine output defined as >40 mL/kg/24 hours.1 The most common cause is primary polydipsia. Polydipsia can also be a compensatory mechanism for fluid loss, such as the osmotic diuresis of uncontrolled diabetes mellitus. Global polyuria can also result from diabetes insipidus.13

Nocturnal polyuria

Nocturnal polyuria (NP) is increased urine production at night. Nocturnal polyuria exists when the nocturnal urine volume represents >20% of the 24 hour voided volume in younger adults and >33% in patients aged 65 years and over. The 24 hour voided volume is normal.13 Nocturnal polyuria is present in up to 80% of patients with nocturia and can be easily overlooked if a FVC is not completed.7

Nocturnal polyuria can be caused by low nocturnal ADH levels. This can occur from central nervous system lesions that affect the hypothalamicpituitary axis, but it can also occur in elderly patients without specific central nervous system pathology.

Peripheral oedema can result in NP as the accumulated fluid is redistributed to the intravascular compartment once recumbent in bed. This excess fluid is then excreted by the kidneys.11

Bladder storage disorders

Lower urinary tract pathology may present with frequent small volume voids often in association with other lower urinary tract symptoms (LUTS). Any structural or functional pathology that affects the reservoir capacity of the bladder can increase voiding frequency. Potential pathologies are listed in Figure 1.

Bladder storage disorders tend to predominate among younger patients while NP predominates in older patients.14 The presence of other LUTS suggests lower urinary tract pathology, however many patients (especially the elderly) have a mixed pattern of disease with multiple contributing factors.15 Nocturia in males should not be assumed to be due to benign prostatic hypertrophy (BPH). Nocturia is the least specific symptom of BPH and prostatic pathology is unlikely to exist in the absence of voiding symptoms such as poor stream and hesitancy.7

Sleep disorders

Patients who constantly wake at night for other reasons may feel the need to void. These patients pass small volumes of urine and have a similar FVC to a bladder storage disorder.1 It is important to determine whether the primary reason for waking was to void.10 If a sleep disorder is suspected, referral to a sleep physician should be considered.

Clinical evaluation

It is important to enquire about nocturia as it is often under reported. Many patients will not present with the complaint of nocturia, but with fatigue related symptoms. Some may not raise the issue as they feel embarrassed, do not realise treatment is available or may perceive it as a normal part of ageing.9

Given the wide range of possible aetiologies, the key diagnostic tool is the FVC. History and examination give important clues to the underlying pathological processes (Table 2).

Management

Management should be directed to correctly identifying the underlying aetiology. Most individual treatments reduce nocturia by less than one episode per night compared to placebo. A combined approach consisting of behavioural, medical and surgical interventions, where appropriate, has greater benefit.15

Lifestyle modifications

Appropriate lifestyle modification should be recommended (Table 4).

Table 4. Recommended lifestyle modifications to manage nocturia

Avoid drinking caffeine and alcohol in the evening

Limit excessive fluid and food intake 3 hours before bedtime

Evening leg elevation

Pre-emptive voiding

Medication timing (moving diuretic doses to the mid-afternoon. Calcium channel blockers, especially hydropyridines, to be administered in the morning rather than evening for symptomatic patients)

Optimisation of the sleep environment

Exercise program

Attention to psychological, financial and family concerns

The sleep environment should be optimised with attention to room temperature, noise, lighting and consistent times of going to bed. Regular exercise can lead to deeper sleep and increases the bladder volume arousal threshold.10 Dealing with psychological factors, financial and family issues have been shown to improve sleep quality.16,17 Lower limb elevation before going to bed is useful in patients with peripheral oedema.15 Dosage times for diuretics should be moved from evening to mid afternoon.

Sedatives are best reserved for sleep disorders rather than nocturia, although a short acting hypnotic may be beneficial for patients who wake early in the night and find it difficult to return to sleep.10

Specific treatment

Global polyuria

Primary polydipsia can be effectively managed with fluid restriction. Patients with poorly controlled diabetes mellitus or diabetes insipidus will benefit from an endocrinology assessment.

Nocturnal polyuria

Underlying medical causes (eg. congestive cardiac failure, chronic kidney disease and obstructive sleep apnoea [OSA]) should first be identified and treated. If patients already have these conditions, new onset nocturia should prompt a management review. Patients suspected of OSA will benefit from referral to a sleep physician for a sleep study and tailored treatment.

Nasal desmopressin (an antidiuretic hormone [ADH] analogue) is currently used in Europe for the treatment of NP. It is hypothesised to rectify defects in circadian secretion of ADH and has been shown to reduce the number of nocturnal voids in patients with NP.18 However, elderly patients are at risk of hyponatraemia and use is contraindicated in congestive cardiac failure and renal failure.19 Desmopressin is not currently listed for use in Australia for treating nocturia, except where associated with diabetes insipidus.

Bladder storage disorders

These patients require urological assessment. The urologist may perform further investigations such as uroflowmetry/postvoid residual urine measurement, urodynamics or cystoscopy, depending on the clinical scenario.

In male patients with bladder outlet obstruction, treatments are less effective at improving nocturia than for obstructive LUTS such as slow stream and hesitancy.20,21 α-blockers (eg. prazosin, tamsulosin, alfuzosin) have shown a modest improvement in the number of nocturic episodes.20 Gains tend to be noticed almost immediately and correlate with the severity of nocturia.20 α-blockers must be prescribed with caution, especially in the elderly due to associated postural hypotension.

Prostatic surgery (eg. transurethral resection of prostate [TuRP], laser prostatectomy) in appropriately selected patients with bladder outlet obstruction reduces episodes of nocturia.22 Surgery appears to be more effective in younger patients and in those with more severe obstruction.10 Surgical results are less successful in mixed nocturia, especially those with NP.

A trial of antimuscarinic therapy (eg. oxybutynin, tolterodine, darifenacin, solifenacin) can be of benefit to patients with symptoms suggestive of overactive bladder. Patients who derive most benefit are those whose nocturic episodes are associated with urgency.7

Key points

Nocturia is common over the age of 40 years and its prevalence is similar in both males and females.

Nocturia can have a profound impact on quality of life and has been shown to be a predictor of mortality.

Prostatic disease should not be assumed to be the cause of nocturia in men.

Nocturia may signify the presence of an undiagnosed medical condition or suboptimal management of a known medical condition. Cardiovascular, respiratory, renal, neurological and endocrine causes may be relevant.

A multimodal approach to treatment yields the most effective results because aetiology is often multifactorial.

Appropriate behavioural modifications should be recommended to all patients.

Conflict of interest: A/Prof Prem Rashid has acted as a consultant for Coloplast, AstraZeneca, Abbott, Ipsen and Sanofi Aventis pharmaceuticals, as well as, the Neotract Corporation. He was a Preceptor in Advanced Laparoscopic Urology with Professor Inderbir S. Gill, (then) Head of the Section of Laparoscopic and Robotic Surgery and Chairman, Glickman Urological Institute, Cleveland Clinic Foundation via a 2006 grant from the Australasian Urological Foundation.

Acknowledgements

Thanks to Dr Mohan Vattekad, Director of Nephrology, Port Macquarie Base Hospital, for his helpful comments on the content of this article.

Downloads

Help with downloads

Opening or saving files

Files on the website can be opened or downloaded and saved to your computer or device.

To open click on the link, your computer or device will try and open the file using compatible software.

To save the file right click or option-click the link and choose "Save As...". Follow the prompts to chose a location.

Types of file

PDF Most of the documents on the RACGP website are in Portable Document Format (PDF). These files will have "PDF" in brackets along with the filesize of the download. To open a PDF file you will need compatible software such as Adobe Reader. If you do not have it you can download Adobe Reader free of charge.

DOC Some documents on this site are in Microsoft Word format. These will have "DOC" in brackets along with the filesize of the download. To view these documents you will need software that can read Microsoft Word format. If you don't have anything you can download the MS Word Viewer free of charge.

Downloads

Help with downloads

Opening or saving files

Files on the website can be opened or downloaded and saved to your computer or device.

To open click on the link, your computer or device will try and open the file using compatible software.

To save the file right click or option-click the link and choose "Save As...". Follow the prompts to chose a location.

Types of file

PDF Most of the documents on the RACGP website are in Portable Document Format (PDF). These files will have "PDF" in brackets along with the filesize of the download. To open a PDF file you will need compatible software such as Adobe Reader. If you do not have it you can download Adobe Reader free of charge.

DOC Some documents on this site are in Microsoft Word format. These will have "DOC" in brackets along with the filesize of the download. To view these documents you will need software that can read Microsoft Word format. If you don't have anything you can download the MS Word Viewer free of charge.

Australian Family Physician (incorporating Annals of General Practice)
is published by The Royal Australian College of General Practitioners,
100 Wellington Parade, East Melbourne, Victoria 3002, Australiaafp@racgp.org.au

The views expressed by the authors of articles in Australian Family Physician are their own and not
necessarily those of the publisher or the editorial staff, and must not be quoted as such. Every care is
taken to reproduce articles accurately, but the publisher accepts no responsibility for errors, omissions or
inaccuracies contained therein or for the consequences of any action taken by any person as a result of
anything contained in this publication. The content of any advertising or promotional material contained
within, or mailed with, Australian Family Physician is not necessarily endorsed by the publisher.